1. Field of the Invention
The present invention relates to a novel herbicidal pyrimidine derivative. More particularly, the present invention relates to a novel herbicidal 2-(4,6-dimethoxypyrimidin-2-yl)oxybenzoic acid imino ester derivative represented by the following general formula (I): ##STR1## in which R.sub.1 represents 4,6-dimethoxy-2-pyrimidinyl, C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 alkenyl, acyl, C.sub.1 -C.sub.4 alkyl sulfonyl or heteroarylmethyl;
R.sub.2 represents hydrogen, halogen, cyano, nitro, C.sub.1 -C.sub.8 alkyl, C.sub.1 -C.sub.8 alkoxy, C.sub.1 -C.sub.8 alkylthio, C.sub.1 -C.sub.8 alkoxycarbonyl, C.sub.2 -C.sub.4 alkenyloxycarbonyl, arylmethoxycarbonyl, heteroarylmethoxycarbonyl, C.sub.1 -C.sub.4 alkylaminocarbonyl, aryl-C.sub.1 -C.sub.4 alkylaminocarbonyl, heteroarylmethylaminocarbonyl, aryl, C.sub.2 -C.sub.8 alkenyl, C.sub.3 -C.sub.6 cycloalkyl, benzyl, aryloxy, arylthio or C.sub.1 -C.sub.8 alkylcarbonyl; and PA1 R.sub.3 represents phenyl group which can be optionally substituted with substituent selected from the group consisting of halogen, cyano, nitro, C.sub.1 -C.sub.4 alkyl, C.sub.3 -C.sub.6 cycloalkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkenyloxy, C.sub.1 -C.sub.4 alkylthio, amino which can be substituted with C.sub.1 -C.sub.4 alkyl, aryl, aryloxy, C.sub.1 -C.sub.4 acyl, C.sub.1 -C.sub.4 acyloxy and C.sub.2 -C.sub.4 alkenyl, or represents a group of formula --COR.sub.4 wherein R.sub.4 represents hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 alkenyl, C.sub.3 -C.sub.6 cycloalkyl, benzyl, aryl, C.sub.1 -C.sub.4 alkoxy, C.sub.2 -C.sub.4 alkenyloxy, C.sub.3 -C.sub.6 cycloalkyloxy, benzyloxy, aryloxy, C.sub.1 -C.sub.4 alkylthio, C.sub.2 -C.sub.4 alkenylthio, C.sub.3 -C.sub.6 cycloalkylthio, benzylthio, arylthio, amino which can be substituted with C.sub.1 -C.sub.4 alkyl, amino which can be substituted with aryl, or amino which can be substituted with arylmethyl. PA1 R.sub.2 represents hydrogen, halogen, cyano, nitro, C.sub.1 -C.sub.8 alkyl, C.sub.1 -C.sub.8 alkoxy, C.sub.1 -C.sub.8 alkylthio, C.sub.1 -C.sub.8 alkoxycarbonyl, C.sub.2 -C.sub.4 alkenyloxycarbonyl, arylmethoxycarbonyl, heteroarylmethoxycarbonyl, C.sub.1 -C.sub.4 alkylaminocarbonyl, aryl-C.sub.1 -C.sub.4 alkylaminocarbonyl, heteroarylmethylaminocarbonyl, aryl, C.sub.2 -C.sub.8 alkenyl, C.sub.3 -C.sub.6 cycloalkyl, benzyl, aryloxy, arylthio or C.sub.1 -C.sub.8 alkylcarbonyl; and PA1 R.sub.3 represents phenyl group which can be optionally substituted with substituent selected from the group consisting of halogen, cyano, nitro, C.sub.1 -C.sub.4 alkyl, C.sub.3 -C.sub.6 cycloalkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.2 -C.sub.4 alkenyloxy, C.sub.1 -C.sub.4 alkylthio, amino which can be substituted with C.sub.1 -C.sub.4 alkyl, aryl, aryloxy, C.sub.1 -C.sub.4 acyl, C.sub.1 -C.sub.4 acyloxy and C.sub.2 -C.sub.4 alkenyl, or represents a group of formula --COR.sub.4 wherein R.sub.4 represents hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 alkenyl, C.sub.3 -C.sub.6 cycloalkyl, benzyl, aryl, C.sub.1 -C.sub.4 alkoxy, C.sub.2 -C.sub.4 alkenyloxy, C.sub.3 -C.sub.6 cycloalkyloxy, benzyloxy, aryloxy, C.sub.1 -C.sub.4 alkylthio, C.sub.2 -C.sub.4 alkenylthio, C.sub.3 -C.sub.6 cycloalkylthio, benzylthio, arylthio, amino which can be substituted with C.sub.1 -C.sub.4 alkyl, amino which can be substituted with aryl, or amino which can be substituted with arylmethyl. PA1 R.sub.1 represents 4,6-dimethoxy-2-pyrimidinyl; PA1 R.sub.2 represents hydrogen, halogen, cyanophenyl, C.sub.1 -C.sub.8 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkylthio, C.sub.1 -C.sub.4 alkoxycarbonyl, mono- or di-C.sub.1 -C.sub.4 alkylaminocarbonyl, phenyl-C.sub.1 -C.sub.2 alkylaminocarbonyl wherein the phenyl moiety can be optionally substituted with halogen, C.sub.1 -C.sub.2 alkyl or C.sub.1 -C.sub.2 alkoxy, furylmethylaminocarbonyl or phenyl; and PA1 R.sub.3 represents phenyl group which is unsubstituted or substituted with halogen, cyano, nitro, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, allyloxy, C.sub.1 -C.sub.4 alkylthio, amino which can be substituted with C.sub.1 -C.sub.4 alkyl, phenoxy, benzyloxy or acetoxy, or represents a group of formula --COR.sub.4 wherein R.sub.4 represents C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkyl, benzyloxy or benzylamino. PA1 R.sub.1 represents 4,6-dimethoxy-2-pyrimidinyl; PA1 R.sub.2 represents hydrogen, chloro, cyanophenyl, C.sub.1 -C.sub.8 alkyl, methoxy, methylthio, C.sub.1 -C.sub.2 alkoxycarbonyl, propylaminocarbonyl, dimethylaminocarbonyl, benzylaminocarbonyl wherein the benzyl moiety is optionally substituted with chloro, methyl or methoxy, 2'-phenylethylaminocarbonyl, furylmethylaminocarbonyl or phenyl; and PA1 R.sub.3 represents phenyl group which is unsubstituted or substituted with a substituent selected from the group consisting of chloro, fluoro, cyano, nitro, methyl, methoxy, ethoxy, butoxy, allyloxy, methylthio, dimethylamino, phenoxy, benzyloxy or acetoxy, or represents a group of formula --COR.sub.4 wherein R.sub.4 represents methoxy, ethoxy, methyl, benzyloxy or benzylamino. PA1 R.sub.1 represents C.sub.1 -C.sub.2 alkyl, C.sub.2 -C.sub.4 alkenyl, allyl, acetyl, methylsulfonyl, thienylmethyl or furylmethyl; PA1 R.sub.2 represents hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkylthio, cyano or C.sub.1 -C.sub.4 alkoxycarbonyl; and PA1 R.sub.3 represents phenyl group which is unsubstituted or substituted with C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy or C.sub.2 -C.sub.4 alkenyl. PA1 R.sub.1 represents methyl, ethyl, allyl, acetyl, methylsulfonyl, thienylmethyl or furylmethyl; PA1 R.sub.2 represents hydrogen, methyl, methylthio, cyano or methoxycarbonyl; and PA1 R.sub.3 represents phenyl group which is unsubstituted or substituted with methyl or methoxy. PA1 X represents a halogen atom.
The present invention also relates to a process for preparation of the compound of formula (I), as defined above, and to a herbicidal composition containing the compound of formula (I) as an active ingredient.
2. Background Art
In the prior art, it has been well known that 2-phenoxypyrimidine or (pyrimidin-2-yl)oxybenzene derivatives are useful as a herbicide (see Agr. Biol. Chem., Vol. 30, P.896 (1966); Japanese Laid-open Patent Publication No. 79-55729; U.S. Pat. Nos. 4,248,619 and 4,427,437). Recently, it has also been noted that among numerous compounds developed on the basis of 2-phenoxypyrimidine a 2-(pyrimidin-2-yl)oxybenzoic acid derivative has an excellent herbicidal activity (see European Patent Publication Nos. 223,406, 249,708, 287,072, 287,079, 315,889, 321,846, 330,990, 335,409, 346,789, 363,040, 402,751, 435,170, 435,186, 457,505, 459,243 and 468,690, British Patent Publication No. 2,237,570 and German Patent Publication No. 3942476). Those prior known compounds show a mechanism of action similar to that of sulfonylurea derivatives, imidazolinol derivatives and triazolepyrimidine derivatives which have been known as an inhibitor of amino acid biosynthesis, and also have a merit of being easily prepared with their simple structures.
Herbicidal activity and selectivity on useful crops of those known compounds are varied with the kind of substituents on the benzene ring of 2-(pyrimidin-2-yl)oxybenzoic acid or with the type of benzoic acid ester derivatives. Accordingly, the development of novel herbicides has placed the focus on the introduction of different substituents into the benzene ring of 2-(pyrimidin-2-yl)oxybenzoic acid and/or the formation of novel ester derivatives.
Thus, the present inventors have extensively studied to develop a novel ester derivative based on 2-(pyrimidin-2-yl)oxybenzoic acid, which shows a high herbicidal activity and selectivity on weeds but has no phytotoxicity on useful crops. According to this, we have identified that a certain imino ester compound having an aromatic ring or carbonyl moiety such as the compound of formula (I), as defined above, can exhibit an excellent herbicidal activity in comparison to the prior herbicidal ester derivatives, and then completed the present invention.
In addition, 2,6-di(pyrimidin-2-yl)oxybenzoic acid derivatives having an alkylimino ester structure which is similar to that of the compound of formula (I) according to the present invention have also been described in the prior art (see European Patent Publication No. 321,846). However, iminoester derivatives having an aromatic ring or carbonal moiety which is the same as that of the compound of formula (I) according to the present invention have never been disclosed and further, cannot be synthesized by the methods for preparing alkyliminio ester derivatives as disclosed in the said European Publication, even though, in some particular cases, they can be synthesized only with an extremely low yield (less than 5%). Accordingly, the present inventors have also developed, as well as an imino ester derivative (I) having an aromatic ring, a novel method for preparation thereof.
Thus, it is an object of the present invention to provide a novel herbicidal 2-(4,6-dimethoxypyrimidin-2-yl)oxybenzoic acid imino ester derivative having the general formula (I), as defined above.
It is another object of the present invention to provide a process for preparing the novel 2-(4,6-dimethoxypyrimidin-2-yl)oxybenzoic acid imino ester derivative of formula (I).
Further, it is still another object of the present invention to provide a herbicidal composition containing at least one of the novel 2-(4,6-dimethoxypyrimidin-2-yl)oxybenzoic acid imino ester derivative of formula (I) as an active ingredient.
It is further object of the present invention to provide a novel intermediate pyridine thio ester compound having the general formula (II) as defined below, which can be used as a starting material for preparing the compound of formula (I) of the present invention.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more pertinent features and applications of the invention. Other many beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a more thorough understanding of the invention may be had by referring to the disclosure of invention, in addition to the scope of the invention defined by the claims.